Transcript for Why This Man Used a Bulldozer to Terrorize His Neighborhood

neighbors from hell? It's like a movie scene. It doesn't get crazier than this. I can't understand you when you're screaming. It's your neighbor? Neighbors terrorized by a bully in a bulldozer. I was afraid I was going to die. Dan and Mary Davis and bob porter are retirees who came to Washington looking for a bit of a break. Clinging to the northern shore of the olympic peninsula, a port of call for lumber men and fishermen. Before we meet the neighbor from the dark side, let's trace his path fr path. Reporter: And this is where it wound up -- next door. He shoved my house through the fence, collapsed both their storage buildings. It was way over there, and it ended up here. And that's my house there. He headed toward this small house here and it looks to me like he destroyed that house. Reporter: To say nothing of Dan's pickup truck, which in the end, could have been carried away with a spatula. All of this, courtesy of a bulldozer driven by a very angry logger -- their neighbor, Barry swegle. I talked with his brother Jeff. Barry's actually an easygoing guy. I'm almost smiling, just because of the juxtaposition of -- I'm picturing him up on the dozer, knocking down houses as an easygoing guy. I'm trying to get my head wrapped around that. Well, I guess things change. You know, if somebody makes you mad enough, you snap. You do things you probably regret. Yeah. I think that's what happened here. He, he snapped. Reporter: Long before Barry snapped, crackled and popped his way through this neighborhood, a fella down in Colorado climbed in an armor-clad bulldozer in 2004 and laid waste to a good chunk of the town of Granby. When the dozer's engine finally died, the man killed himself. Miraculously, up here in port Angeles no one was injured in Barry's wrecking spree. But what set him off? What do you think was his big gripe? Well, it really boils down to one of the neighbors and that's Dan Davis. Barry kept telling me that Dan was pissing him off, doing little things to get him mad. Reporter: They say good fences make good neighbors. Well, not in this case. Seems Mr. Davis had been trying to build a fence between his property and Barry swegle's driveway. How far back does that go? Oh, it goes back for years over that fence up there. I think he wanted something that didn't belong to him and he was mad because we were fixing it. Property lines are the most heated dispute between neighbors because people believe in lines and yet both neighbors believe the line is different. Reporter: Real estate mogul Barbara Corcoran has seen so many of these disputes spin out of control, she should be given a permanent seat on the U.N. Security council. It takes two to fight. If either of them had handled this intelligently, the whole thing could not have happened. Reporter: Taking the long view, as in "From outer space," there's Dan's property and adjacent to it, Barry's driveway. You can see how Barry's trucks and heavy equipment wore a path across the corner of Dan's property. Barry had logging equipment. His only way in and out was through this road. Reporter: Yeah. So, you need a pretty good-sized entrance to make the turn. Reporter: Make the corner. He'd knock it down. We put it back. Reporter: Now, Dan Davis was not about to be intimidated, but he's 75 with a bum knee and bad eyesight. By contrast, Barry sweigle is a 245-pound Paul Bunyan in love with machinery. Instead of "Babe the blue ox," rusting carcasses of his old toys line his driveway. If you knew Barry, you know he's a big boy. So you know I'm 300 pounds and I don't -- I'd be kinda scared of him if he went sideways. Reporter: Sideways, backwards, inside or out -- Jason says there was something else that made Barry dangerous. He didn't know me from Adam and just flat-out said he had a meth problem, you know, and he's trying to get help, and nobody ll wi help him. Reporter: Both Barry's brother and local authorities confirm Barry had a history of drug use and a penchant for paranoia. He said we were the leaders of a gang that was coming over. They were coming through our property. And, uh -- Stealing his fuel. Stealing his fuel. And his batteries. He thought that this mobile home had been surveilling him in there, the government or somebody was watching him. Reporter: Even law enforcement had a growing file on the odd fellow living at 2313 east Ryan drive. He was out here with his backhoe, with his excavator, digging up his yard. And digging 20-foot-deep holes in this driveway right behind us. Reporter: He was just digging holes? Just digging holes. Reporter: Barry's bizarre brew of anger, heavy machines and paranoia finally came to a full boil on an otherwise beautiful morning last may, when he turned his attention back to his neighbor Dan and that fence of his. He was saying something. I couldn't understand him. He was just bouncing up and down, giving me the finger. Well, the first time in my life I ever did it, I gave him the finger back. Then, he drove off. And then I called the sheriff -- Communications. Susan. Yeah, Susan, my name is Dan Davis -- -- And I says, "Well, something's gonna happen here." I says, "Barry has been tearing our fence down for 10 to 12 years and I think he's gonna do it again." He just drove by here and he just harassed the hell out of me. About two and a half hours later, then things basically hit the fan. He's smashing my house! Smashing your house? Reporter: When we come back, forget the fence -- he's going to take out the whole neighborhood. Yeah, now he's tearing the neighbor's place down. Holy Jesus.

This transcript has been automatically generated and may not be 100% accurate.

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